Observation of a red-blue detuning asymmetry in matter-wave superradiance

TL;DR

This paper reports the first experimental observation of a detuning asymmetry in matter-wave superradiance, showing suppression with blue-detuned light and symmetry restoration in dilute gases, challenging previous theoretical predictions.

Contribution

It provides the first experimental evidence of detuning asymmetry in matter-wave superradiance, revealing new insights into the process's dependence on pump laser detuning.

Findings

Superradiance is suppressed with blue-detuned pump light in condensates.

A detuning asymmetry exists, breaking the expected symmetry.

Symmetry is restored in dilute atomic gases.

Abstract

We report the first experimental observations of strong suppression of matter-wave superradiance using blue-detuned pump light and demonstrate a pump-laser detuning asymmetry in the collective atomic recoil motion. In contrast to all previous theoretical frameworks, which predict that the process should be symmetric with respect to the sign of the pump-laser detuning, we find that for condensates the symmetry is broken. With high condensate densities and red-detuned light, the familiar distinctive multi-order, matter-wave scattering pattern is clearly visible, whereas with blue-detuned light superradiance is strongly suppressed. In the limit of a dilute atomic gas, however, symmetry is restored.